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    Characterization of volatiles in Beaten cheeses Bieno sirenje by SPME/GC-MS: Influence of geographical origin
    (Serbian Chemical Soc, 2014) Sulejmani, Erhan; Rafajlovska, Vesna; Guneser, Onur
    In this study, the volatile profiles of an economically important type of cheeses for the FYR Macedonian dairy sector were characterized. A total of eighteen samples belonging to 6 different geographical regions of Beaten cheese, including cheeses from Kumanovo, Tetovo, Struga, Resen, Veles and Radovis, were comparatively studied for their volatile profiles. Sixty one volatile compounds were identified in the cheeses by solid-phase micro-extraction combined with gas chromatography mass spectrometry. The results are discussed based on their chemical classes (17 esters, 9 ketones, 10 acids, 8 alcohols, 6 terpenes and 11 miscellaneous compounds). Acids, esters and alcohols were the most abundant classes identified and were highly dependent on the geographical origin of the cheeses. Beaten cheese from Struga had the highest levels of carboxylic acids, ketones, alcohols, esters and terpenes. The Beaten cheese of other geographical origin had low levels of volatiles, probably due to the effects of the variable characteristics of the employed milk and differences in the cheese making processes, which affected the biochemical processes. The results suggested that each cheese from different geographical regions had a different volatiles profile and that the manufacturing technique and the ripening stage of the cheeses played major roles in determining the distribution of the volatile compounds.
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    Cold pressed capia pepperseed (Capsicum Annuum L.) oils: Composition, aroma, and sensory properties
    (Wiley, 2015) Yılmaz, Emin; Arsunar, Emel Sevgi; Aydeniz, Buket; Guneser, Onur
    In this study, cold press-produced capia pepperseed oil samples were characterized. Pre-roasting and enzyme treatment against control group (no pre-treatment) were applied to the seeds prior to cold pressing, and the oil yield, meal, and oil quality parameters were examined. The physico-chemical parameters (refractive index, viscosity, turbidity, specific gravity, color, free acidity, peroxide and iodine values, antioxidant capacity, total phenolic content, and energy value), components composition (fatty acid, sterol, and tocopherol), thermal parameters (melting and crystallization temperatures and enthalpies), volatile aromatics composition, sensory properties (Flavor Profile Analysis), and consumer perception (hedonic test) of the oil samples were accomplished. It was found that cold pressing is low in efficiency, and oil sensory quality and consumer acceptability levels were also low. Although pre-roasted seeds yielded a little more oil and had better sensory quality, it was determined that these oils need at least a deodorization or a physical refining for acceptable sensory quality. Practical applications: The results of this study indicated that capia pepperseeds obtained as waste during vegetable processing can be used as an alternative source for cold pressed oils and a raw material for animal feed. Moreover, these seed oils have economical impact due to their essential fatty acid (linoleic acid, 71.13%), sterol, and tocopherol content. Based on the sensory findings, full or partial refining is recommended in order to increase the sensory quality of the pepperseed oil.
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    Effect of emulsifiers on oil separation problem and quality characteristics of Tahin Helva during storage
    (Springer India, 2014) Guneser, Onur; Zorba, Murat
    Tahin helva is one of Turkish traditional confectionary foods. Sesame paste, sugar syrup and soapwort extract were used for tahin helva's production. The purpose of this study was to solve the oil separation problem occurred in tahin helva by using food additives permitted as an emulsifier for tahin helva in the Turkish and EU Codex. Sorbitan tristearate (STS), sorbitan monopalmitate (SMP) and their combinations (STS:SMP, 1:1) were added to tahin helva, then helva samples were stored at the storage temperatures of 20 A degrees C, 30 A degrees C, and 40 A degrees C. The emulsifiers did not have any effect on physical, chemical and sensory properties of tahin helva except on its oil content, whereas storage temperature and storage time had effects on those properties of helva. STS:SMP combination was found to be statistically more effective than SMP and STS formulations in preventing oil separation. Penetration force of tahin helva has increased by increasing the storage temperature and storage time. It was found that there was a decrease in -a colour value of helva through the storage time at 20 A degrees C and 30 A degrees C, while there was an increase in that value at 40 A degrees C. The highest change in the moisture content of all helva samples through storage was observed at the storage temperature of 20 A degrees C. Sensory scores for appearance, texture and flavour characteristics of helva have decreased significantly during the storage period.
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    Fermented Spirulina products with Saccharomyces and non- Saccharomyces yeasts: Special reference to their microbial, physico-chemical and sensory characterizations
    (Elsevier, 2022) Sahin, Busra; Hosoglu, Muge Isleten; Guneser, Onur; Karagul-Yuceer, Yonca
    Innovative products produced from various sources through fermentation processes have been a resurgence of interest. This study was designed to determine the performance of fermented Spirulina (FS) products by three different yeast species including Debaryomyces hansenii, Kluyveromyces marxianus and Saccharomyces cerevisiae and investigate the microbial, physicochemical and sensory characteristics of products. The results showed that the increase in yeast cell number was around 3 log after 48 h fermentation in Spirulina medium without additional carbon source. Protein bands with a molecular weight of-51 kDa seemed less visible and bands 14-22 kDa disappeared after 48 h fermentation by K. marxianus showed strong hydrolysis of proteins during fermentation. The amino acid compositions of the three kinds of FS were different also compared to unfermented Spirulina (unFS). Glutamic acid, methionine, lysine, isoleucine and valine became more dominant in FS samples. According to GC-MS analysis, there was a decrease in the concentration of pyrazine, ketone and aldehyde compounds of FS compared to unFS. The flavor notes of seaweed, cardboard, earthy/muddy and cereal/ straw were found to be the highest in unFS than in FS detected by panelists during sensory evaluations. FS by K. marxianus is highly characterized as having the lowest seaweed and umami flavor attributes and higher fermented and rose attributes. Finally, the current study revealed that the potential of Spirulina biomass to be a suitable substrate for yeasts and fermentation of Spirulina with different yeast species led to different kinds of products.
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    Formation kinetics of hydroxymethylfurfural and brown coloured compounds in goat milk during heating
    (Wiley, 2013) Guneser, Onur; Toklucu, Aysegul Kirca; Karagul-Yuceer, Yonca
    The formation of hydroxymethylfurfural, nonenzymatic brown coloured compounds and free sulphydryl groups in goat milk was studied during heating at 7595 degrees C. Analysis of kinetic data suggested that formation of hydroxymethylfurfural and nonenzymatic brown coloured compounds followed zero order reaction kinetics, while formation of free sulphydryl groups during heating varied depending on heating time. A good linear correlation (r = 0.839) was found between brown coloured compounds and hydroxymethylfurfural content in milk samples during heating. Activation energies (Ea) for the formation of hydroxymethylfurfural and nonenzymatic brown coloured compounds were 96.31 and 69.79 kJ/mol, respectively.
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    Influence of Storage on Physicochemical and Volatile Features of Enriched and Aromatized Wax Organogels
    (Wiley, 2015) Ogutcu, Mustafa; Yılmaz, Emin; Guneser, Onur
    In this study, virgin olive oil (VOO) organogels were produced with beeswax (BW) and sunflower wax (SW) and enriched with beta-carotene, vitamin D-3 and E as well as aromatized with strawberry, banana, and butter aromas. The physicochemical, thermal, structural, and sensorial properties of the fresh organogel samples were determined. The peroxide values, antioxidant activities, firmness, and volatile compositions of the fresh samples and those stored for 3 months were also determined. The organogels were not only stable, uniform, and homogenous during the storage period but also the added components did not affect the organogel properties. The panel defined three appearance, four texture, three mouthfeel, four aroma, and four flavor terms to describe the organogels sensorially. Moreover, the added aroma (banana, strawberry, and diacetyl-butter) components of the fresh and stored organogels were quantified by GC/MS-SPME. In conclusion, these results demonstrated that beeswax and sunflower wax are very suitable to preserve the aromatic characteristics of these types of spreadable products.
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    Optimizing bioreactor conditions for Spirulina fermentation by Lactobacillus helveticus and Kluyveromyces marxianus: Impact on chemical & bioactive properties
    (Elsevier Sci Ltd, 2024) Yay, Cansu; Cinar, Zeynep Ozlem; Donmez, Serhat; Tumer, Tugba Boyunegmez; Guneser, Onur; Hosoglu, Muge Isleten
    This study focused on optimizing the production of fermented Spirulina (FS) products using a bioactivity-guided strategy with Lactobacillus helveticus B-4526 and Kluyveromyces marxianus Y-329 in a 3-L bioreactor. Various operating conditions, including aeration rates and pH modes, were tested. While both microorganisms thrived under all conditions, the cascade mode, controlling dissolved oxygen, enhanced protein hydrolysis and antioxidant activity, as confirmed by SDS-PAGE and DPPH/TEAC assays, respectively. Screening revealed that cascade FS significantly decreased viability of colon cancer cells (HT-29) in a dose-dependent manner, with up to a 72 % reduction. Doses <= 500 mu g mL- 1 of cascade FS proved safe and effective in suppressing NO release without compromising cellular viability. Additionally, cascade FS exhibited diverse volatile organic compounds and reducing the characteristic seaweed aroma. These findings highlight cascade FS as a promising alternative food source with improved bioactive properties, urging further exploration of its bioactive compounds, particularly bioactive peptides.
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    Physico-chemical, Sensory and Aromatic Properties of Cold Press Produced Safflower Oil
    (Springer, 2014) Aydeniz, Buket; Guneser, Onur; Yılmaz, Emin
    In this study, seeds from the safflower variety called Din double dagger er were roasted and microwaved before oil extraction by cold pressing. Some physico-chemical analyses (moisture, ash, oil content and color) were performed in safflower meals. Physico-chemical properties (refractive index, viscosity, turbidity, specific gravity, color, free acidity, peroxide value, iodine number), nutritional components (total phenolics, antioxidant capacity, tocopherol content), sterol composition and fatty acid composition of produced oils were also determined. Volatile components of the oils were detected by solid-phase microextraction/gas chromatography-mass spectrometry technique. Quantitative descriptive analysis was accomplished with trained panelists by 11 definition terms. Cold pressing yielded less oil than solvent extraction, but oil quality was superior and a refining process was not required. There was no significant difference between samples for fatty acid composition and some physico-chemical parameters. Whereas, microwave treatment caused a decrease in oil turbidity, free acidity, alpha-tocopherol and some sterol contents and an enhancement in total phenolic content, antioxidant capacity and peroxide value. Moreover, microwave treatment led to an increased nutty aroma in the oil. In contrast, isot pepper aroma was decreased by microwave treatment. This study provides very important information about the safflower oils for the first time in the literature.
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    Sensory and Physico-Chemical Properties of Cold Press-Produced Tomato (Lycopersicon esculentum L.) Seed Oils
    (Wiley, 2015) Yılmaz, Emin; Aydeniz, Buket; Guneser, Onur; Arsunar, Emel Sevgi
    In this study, roasted and unroasted (control) tomato seeds were cold pressed and the seeds, oils, and seed presscakes (meals) were analyzed. Some physicochemical properties, total phenolic content and antioxidant capacity, thermal properties, mineral contents, fatty acids, sterols and tocopherols compositions, volatile compounds and sensory evaluation of the tomato seed oils were determined. The tomato seeds contained 3.3 % of ash, 17.3 % of oil and 27.2 % of protein. The cold press oil recovery rate was 7.2 and 10.28 % for control and roasted seeds, respectively. There were eight sensory terms defining the oils together with 34 different aromatic compounds quantified. The volatile compounds furfural, hexanal, benzaldehyde and 2-isobutylthiazole were found with the highest frequency in the samples. Roasted, green and tomato were defined as characteristic sensory terms for tomato seeds oils. Fifteen different minerals, melting and crystallization temperatures and enthalpies of the oil samples were also quantified. This study provides important data for the tomato seed oils, and proves that pre-roasted tomato seed oils are high quality, nutritious and aromatics oils with higher levels of consumer acceptability.
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    Volatile compounds and proteolysis in traditional Beaten (Bieno sirenje) ewe's milk cheese
    (Wiley, 2014) Sulejmani, Erhan; Rafajlovska, Vesna; Guneser, Onur; Karagul-Yuceer, Yonca; Hayaloglu, Ali A.
    Beaten ewe's milk cheese is a traditional autochthonous type of cheese manufactured in Macedonia with a relatively high nutritional value and sensory characteristics. The objective of this study was to characterise the gross composition, proteolysis and volatile profiles of the cheese that is supplied from different retails. The ranges for gross composition were from 31.53% to 42.83% (w/w) for moisture, 41.99% to 50.98% (w/w) for fat-in-dry matter, 2.03% to 8.25% (w/w) for salt content and 20.74% to 33.35% (w/w) for protein. Proteolysis results showed various levels of soluble nitrogen ranged from 3.15 to 33.50 for water-soluble nitrogen (WSN) and from 1.11% to 6.79% for nitrogen soluble in 12% trichloroacetic acid (TCA-SN). The ranges for total free amino acids were from 1.65 to 8.06 mg Leu/g. Lower proteolysis was observed in the cheese samples due to high salt contents. In total, 65 volatile compounds were identified in Beaten cheese. As a conclusion, the variation of the peptide profile, electrophoresis and volatile contents of Beaten cheeses are due to the lack of standardised manufacture protocols.
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    Volatile metabolites produced from agro-industrial wastes by Na-alginate entrapped Kluyueromyces marxianus
    (Soc Brasileira Microbiologia, 2016) Guneser, Onur; Karagul-Yuceer, Yonca; Wilkowska, Agnieszka; Kregiel, Dorota
    The aim of this study was to evaluate the effects of alginate entrapment on fermentation metabolites of Kluyueromyces marxianus grown in agrowastes that served as the liquid culture media. K. marxianus cells entrapped in Na-alginate were prepared using the traditional liquid-droplet-forming method. Whey and pomaces from processed tomatoes, peppers, and grapes were used as the culture media. The changes in the concentrations of sugar, alcohol, organic acids, and flavor compounds were analyzed using gas chromatography-mass spectrometry (GC-MS) and high pressure liquid chromatography (HPLC). Both free and entrapped, K. marxianus were used individually to metabolize sugars, organic acids, alcohols, and flavor compounds in the tomato, pepper, grape, and acid whey based media. Marked changes in the fermentation behaviors of entrapped and free K. marxianus were observed in each culture. A 1.45-log increase was observed in the cell numbers of free K. marxianus during fermentation. On the contrary, the cell numbers of entrapped K. marxianus remained the same. Both free and entrapped K. marxianus brought about the fermentation of sugars such as glucose, fructose, and lactose in the agrowaste cultures. The highest volume of ethanol was produced by K. marxianus in the whey based media. The concentrations of flavor compounds such as ethyl acetate, isoamyl alcohol, isoamyl acetate, 2-phenylethyl isobutyrate, phenylethyl acetate, and phenylethyl alcohol were higher in fermented agrowaste based media compared to the control. (C) 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda.